"Those with migraine and [their] doctors need to be aware that excessive weight and extreme weight loss are not good for [migraine sufferers], and that maintaining a healthy weight can decrease the risk of migraine," said study corresponding author Dr. B. Lee Peterlin.

She is director of headache research at Johns Hopkins University School of Medicine in Baltimore.

"Healthy lifestyle choices in terms of weight management and diet and exercise are warranted," she added.

Migraines affect about 12 percent of U.S. adults, according to background information from Johns Hopkins. These debilitating headaches are often accompanied by throbbing, nausea and sensitivity to light and sounds.

Peterlin's team evaluated 12 previously published studies with nearly 300,000 people, a process known as a meta-analysis.

The investigators found that obese people were 27 percent more likely to have migraines than people who were at a normal weight.

And those who were underweight were 13 percent more likely to have migraines.

The researchers used the standard definitions of both obesity -- a body mass index (BMI) of 30 or higher -- and underweight, a BMI of less than 18.5. A person who is 5 feet 4 inches tall and weighs 175 pounds has a BMI of 30, while someone of the same height who weighs 105 has a BMI of 18.

In previous research, Peterlin's team found that the link between obesity and migraines was greater for women and for those under the age of 55. This new study reaffirmed those findings.

The new review found that the link between obesity and migraines is a moderate one, Peterlin said. It's similar to the link between migraines and ischemic heart disease, in which the heart doesn't get enough blood, she added.

Peterlin said she can't explain with certainty how body composition affects migraine risk. But, she speculated that fat tissue "is an endocrine organ and like other endocrine organs, such as the thyroid, too much and too little cause problems."

The change in fat tissue that occurs with weight gain or extreme weight loss alters the function and production of several proteins and hormones, Peterlin explained, changing the inflammatory environment in the body. This could make a person more prone to a migraine or it could trigger a migraine, she said.

However, the study only found an association, and not a cause-and-effect relationship, between weight and migraine risk.

The review was published April 12 in the journal Neurology.

Would weight loss or gain help? It's not certain, Peterlin said.

"Limited data in humans show that in both episodic and chronic [migraine sufferers] who are extremely obese and undergo bariatric surgery for other health reasons also have a reduction in headache frequency by over 50 percent," she said. Aerobic exercise has also been shown to decrease headaches.

"What is not yet clear is if it is the weight loss per se or other factors related to exercise that result in the improvement," Peterlin said.
One headache specialist who wasn't involved with the study lauded the findings.

The new analysis is "a valuable addition to the growing body of literature on migraine and body mass index," said Dawn Buse, director of behavioral medicine at the Montefiore Headache Center in New York City.

With her patients, Buse said, she has seen migraine frequency increase with weight gain. And she has also seen improvement in migraines after weight loss, she said.

Buse acknowledged that, while weight loss appears to help, losing weight can be challenging. Health care professionals should discuss with their patients the relationship with migraines, and help them by providing education and referrals for treatments that may help weight loss.